According to results from a large meta-analysis, breast cancer survivors of child-bearing age are less likely than the general population to get pregnant and face greater risk for certain complications, including preterm labor and cesarean section. However, most survivors who do become pregnant are able to deliver healthy babies and experience no adverse effects related to their long-term survival. Eva Blondeaux, MD, Medical Fellow, Oncology, Istituto di Ricovero e Cura a Carattere Scientifico Policlinico San Martino Hospital, Genoa, Italy, and lead investigator, presented these findings at the virtual 2020 San Antonio Breast Cancer Symposium.
“Results of this meta-analysis provide reassuring evidence on the feasibility and safety of conceiving in women with a previous history of breast cancer,” she said, adding that close monitoring is advised for survivors who become pregnant, especially those who were exposed to chemotherapy. In addition, she emphasized the need for complete oncofertility counseling at the time of diagnosis to all women of child-bearing age, even though this recommendation is not included in current guidelines.
The goal of this meta-analysis was to assess the chances of pregnancy in breast cancer survivors, to report on reproductive outcomes, and to assess maternal safety. It was based on 39 studies with a total of 114,473 patients with breast cancer and 8,093,401 women from the general population. Of the 114,473 patients with breast cancer, 7505 had a pregnancy after diagnosis and 107,068 did not.
The investigators compared data from 48,513 survivors with data from 3,289,113 women from the general population on achieving pregnancy. In a pooled analysis of all studies, breast cancer survivors were 60% less likely to become pregnant compared with the general population (P <.001). Among survivors of other cancers, only cervical cancer survivors were significantly less likely to become pregnant than women in the general population (P <.001). Numerically, survivors of any cancer were less likely to become pregnant compared with women in the general population.
No differences in reproductive outcomes were found in spontaneous and induced abortion or pregnancy complications among 3240 breast cancer survivors and 4,814,452 women in the general population. However, breast cancer survivors were at a 14% increased risk for cesarean section (P = .007), and their newborns were at a 50% increased risk for low birth weight (P <.001), a 45% increased risk for preterm birth (P = .006), and a 16% increased risk for being small for gestational age (P = .039).
There was no increased risk for congenital defects in babies born to breast cancer survivors compared with the general population.
An analysis of fetal outcomes by exposure to chemotherapy showed a 62% increased risk for low birth weight, a 60% increase in the risk for preterm birth, and a 51% increase in small for gestational age in newborns of breast cancer survivors treated with chemotherapy versus those who were not.
No detrimental effect of pregnancy on maternal safety was found in 2003 pregnant breast cancer survivors compared with 37,779 nonpregnant breast cancer survivors. Interestingly, disease-free survival improved by 26% in survivors who became pregnant versus those who did not.
In addition, overall survival was improved by 44% when 3261 pregnant survivors were compared with 58,238 nonpregnant breast cancer survivors (P <.001). Pregnancy had no detrimental effect on disease-free survival and overall survival in a subgroup analysis that included BRCA status and nodal status.
Dr Blondeaux noted that although the data support the feasibility and safety of pregnancy in breast cancer survivors, the higher risk for fetal complications indicates that close monitoring is necessary for those who become pregnant, especially if they have received chemotherapy.